Directed nanostructural evolution in Ti0.8Ce0.2N layers grown as a function of low-energy, high-flux ion irradiation

We use a combination of alloying and low-energy ion irradiation during film growth to controllably manipulate the nanostructure of TiN-based layers. Ti0.8Ce0.2N films are grown on SiO2 at 350 degreesC using UHV reactive magnetron sputtering in N-2. The N-2(+)-to-metal ratio incident at the growing film is maintained constant at 15, while the ion energy E-N2(+) is varied from 14 to 45 eV. Films grown with E-N2(+)=14 eV consist of equiaxed nanograins with an average size of 2.0 nm, while layers deposited with E-N2(+)=45 eV exhibit a 2-nm-wide nanocolumnar structure. In both cases, the films are dense, atomically smooth, and have strong 002 texture with low stress. This is in dramatic contrast to TiN films deposited under the same conditions, which are underdense with extremely rough surfaces and consist of broad (similar or equal to 30 nm) columns. We attribute the formation of controlled nanostructures to the interplay between ion-irradiation-induced effects and thermally driven Ce surface segregation, leading to continuous renucleation during film growth. (C) 2004 American Institute of Physics.